Backlight units (BLUs) are used in LCDs for computers, mobile phones, PDAs and the like. BLUs are equipped with a light guide plate as a component providing luminance and uniform lighting.
The light guide plate may be manufactured by injection molding thermoplastic resins.
Conventionally, as a thermoplastic resin for a light guide plate, a polymethylmethacrylate resin, an aromatic polycarbonate resin, or the like was used. However, the polymethylmethacrylate resin is vulnerable to heat generated from devices such as computers, mobile phones, PDA, and the like, due to low heat-resistance thereof. Although the aromatic polycarbonate resin has excellent heat resistance, mechanical characteristics, electrical characteristics, and weather resistance, light transmittance (luminance), color uniformity, and the like are poor.
Accordingly, Japanese Application Pub. No. 2001-215336 introduced copolyestercarbonate having an aliphatic segment to improve light transmittance (luminance). However, there were drawbacks such as reduction of heat resistance.